1. Field of the Invention
The present invention relates to a rectilinear motion rolling guide unit in which track grooves are formed on the longitudinal direction of both side wall surfaces of a long member of a rail, a saddle-shaped slide unit on which track grooves are formed at the positions opposite to the track grooves of the rail, a number of rolling members are inserted between the track grooves, and thereby enabling the rail and slide unit to be slidably moved and, more particularly, to a holding device to prevent the falling of the rolling members in the load range.
2. Description of the Related Background Art
Various kinds of methods of holding the rolling members in the load range (between the track grooves) in such a kind of rectilinear motion rolling guide unit have been proposed and these methods have many advantages. However, according to most of these methods, in the case where the rolling members consist of balls, slits (windows) each having a width which is slightly narrower than the diameter of the ball are formed in the flat plate members, thereby holding the balls.
This structure has advantages such that the holding device has the simple shape and can be easily manufactured. However, there are problems such that a positioning error occures between the holding device and the track groove forming member and the holding device is easily deformed by the external force because it is made of a thin plate, and the like. When sliding, the rolling members come into contact with the holding device, so that the slide resistance is increased. When the slide unit is pulled out of the rail, the balls drop.
On the other hand, there has also been proposed a structure such that no holding device is formed and a holding section is provided for the track groove forming member. However, in the case of the structure such that the track grooves are directly formed on the side wall surfaces of the casing, a grindstone to form the track grooves cannot be inserted into the track grooves since the holding portion under the track grooves becomes an obstacle, so that the track surfaces cannot be formed.